Dermatillomania is a BFRD (Body Focused Repetitive Disorder) that caused people to pick at their skin. This would be interesting to see with a regenerative SCP, where scabs and the like would heal and flake way faster than usual. Is this idea too gross? And what is the general community view on scps based on illnesses, mental or otherwise?

Given that there's no shortage of body horror articles on the site… probably not? I'd be surprised if there isn't already something like this on the mainsite.

And what is the general community view on scps based on illnesses, mental or otherwise?

If it's written well, it stays. Mental illnesses tend to be trickier territory because they're very commonly incorrectly portrayed in popular media (that is, compared to the DSM-V/etc. scientific approach to various disorders) and some people unwittingly write content that comes off as tactless or offensive. There's a fair number of people in the audience who live with some sort of mental illness, so care should be taken to handle those topics with respect.